Kinetics of heat inactivation of Venezuelan equine encephalomyelitis virus

Thermal inactivation of Venezuelan Equine Encephalomyelitis Virus (VEEV) was studied at temperatures from 26 degrees to 55 degrees C. Inactivation of infectivity took place by two thermodynamically different reactions, one of which predominated at temperatures below 44 degrees C and the other at higher temperatures. The presence of 1 or 2 M NaCl stabilized the VEE virus at low temperatures but enhanced the inactivation at high temperatures. This latter effect at temperatures higher than 50 degrees C, is associated with the occurrence of two-component survival curves. The different effects of hypertonic NaCl concentrations at the two ranges of temperature, are related to different mechanisms of inactivation operating at each range (protein denaturation and nucleic acid-RNA breakdown). Different kinetics of thermal inactivation at 55 degrees C were observed between virus strains with different virulence. However, no significant correlations was found between the virulence of the eleven VEE virus strains studied and their thermostability at 37 degres and 55 degrees C.     

Modification of Venezuelan equine encephalomyelitis virus infection in mice by X radiation

A highly virulent strain of Venezuelan equine encephalomyelitis (VEE) virus produced less severe histopathologic changes in brain tissues of mice previously exposed to sublethal total-body x-irradiation than it caused in nonirradiated mice. Prior exposure to 600 R of x-irradiation virtually eliminated the lesions of vasculitis and encephalitis that were found in the infected nonirradiated control mice. Mean peak brain lesion scores generally decreased as radiation exposure dose was increased. Irradiation of mice before inoculation often decreased median time to death, whereas the severity of pathologic changes in brain tissues from inoculated irradiated mice was often reduced, without significantly altering ultimate host survival. The inflammatory response did not appear to have a significant role in clearance of this virus from the brain. There was no evidence that participation of the immune response contributed to total mortality from VEE virus encephalitis, as indicated by the failure of radiation immunosuppression to reduce mortality. Death apparently was caused by the direct cytocidal effects of VEE virus replication.     

Sampling methods for potential epidemic vectors of eastern equine encephalomyelitis virus in Massachusetts

The neurotoxic effect of monosodium L-glutamate (MSG) on the morphologies in the darkly stained sexually dimorphic nucleus of the preoptic area (SDN-POA) and the lighter-staining surrounding area (non-SDN-POA) within the medial preoptic nucleus (MPN) was evaluated. Male and female Long-Evans rats were used. MSG (4 mg/g of body weight) was administered subcutaneously to pups on days 1 and 3 postnatally. Normal saline was used as the vehicle. At the age of 6 months, the rats were sacrificed and the brain tissues were fixed for histological examination. The morphological changes, i.e., total volume, density, total neuron number, neuronal nuclear volume (NNV) and ratio of pyknosis, of the SDN-POA and non-SDN-POA within the MPN, were estimated using the AMS VIDS III semiautomatic image-analytic system. The results indicate that neonatal MSG treatment caused significant neuronal loss and decreases in total volume of the SDN-POA and non-SDN-POA of male and female rats. However, only the SDN-POA of MSG-treated male rats showed a significant increase of pyknosis and decrease of neuronal density. A significant enlargement of NNV in the SDN-POA and non-SDN-POA was observed in the MSG-treated male rats. These results indicate that the MPN shows sex-specific and area-specific changes after neonatal neurotoxicity due to MSG.     

Glycoproteins E2 of the Venezuelan and eastern equine encephalomyelitis viruses contain multiple cross-reactive epitopes

Enzyme immunoassay (EIA) with sixty types of monoclonal antibodies (MAbs) was used to study cross-reactive epitopes on the attenuated and virulent strains of the Eastern equine encephalomyelitis (EEE) and Venezuelan equine encephalomyelitis (VEE) viruses. All three structural proteins of the EEE and VEE viruses were demonstrated to have both cross-reactive and specific antigenic determinants. The glycoprotein E1 of EEE and VEE viruses possesses three cross-reactive epitopes for binding to MAbs. The glycoprotein E2 has a cluster of epitopes for 20 cross-reacting MAbs produced to EEE and VEE viruses. Cross-reactive epitopes were localised within five different sites of glycoprotein E2 of VEE virus and within four sites of that of the EEE virus. There are no cross-neutralising MAbs to the VEE and EEE viruses. Only one type of the protective Mabs was able to cross-protect mice against lethal infection by the virulent strains of the VEE and EEE viruses. Eight MAbs blocked the hemagglutination activity (HA) of both viruses. Antigenic alterations of neutralising and protective sites were revealed for all attenuated strains of the VEE and EEE viruses. Comparative studies of the E2 proteins amino acid sequences show that the antigenic modifications observed with the attenuated strains of the VEE virus may be caused by multiple amino acid changes in positions 7, 62, 120, 192 and 209-213. The escape-variants of the VEE virus obtained with cross-reactive MAbs 7D1, 2D4 and 7A6 have mutations of the E2 protein at positions 59, 212-213 and 232, respectively. Amino acid sequences in these regions of the VEE and EEE viruses are not homologous. These observations indicate that cross-reactive MAbs are capable of recognising discontinuous epitopes on the E2 glycoprotein.     

Clinical aspects of human Venezuelan equine encephalitis in Texas

The Venezuelan equine encephalitis epidemic which occurred in Texas in 1971 produced a wide range of predominantly mild clinical symptoms. This epidemic, which peaked on 13-14 July, was most intensely felt in the far-south counties of Cameron and Hidalgo. In all, 88 laboratory-confirmed human cases were reported to the U.S. Center for Disease Control by the Texas State Department of Health. The ratio of male to female cases was about two to one. An attack of 20.8 cases per 100,000, observed in both the 20-29 and 30-39 age groups, was higher than attack rates experienced by other age groups and by the population at large. Together, Cameron and Hidalgo counties experienced a much higher overall attack rate (21.7 cases por 100,000) than did affected counties in the Corpus Christi area (4.9 cases per 100,000). Knowledge about when various patients were first exposed points to an incubation period ranging from 27.5 hours to four days. In those 79 cases for which clinical data were available, the most common clinical manifestations were found to be fever, severe headache, myalgia, and chills. Evidence of mild to moderate central nervous system involvement was found in 10 out of 25 children and young people under 17 years of age, and in six out of 54 adults. Two children still had residual paralysis six weeks after onset of illness, but by 10 months these sequelae had disappeared. Seven of the 54 adults, however, still complained of tiring easily a year after onset of illness. Leukopenia, as demonstrated by a count of less rhan 4,500 white blood cells per cubic millimeter, was observed in 75 per cent of the patients examined.     

Lymphoreticular and myeloid pathogenesis of Venezuelan equine encephalitis in hamsters

Ultrastructural, histopathologic, and virologic studies of adult hamsters infected with virulent Venezuelan equine encelphalomyelitis (VEE) virus (Subtype I-B) demonstrated precise chronologic and topographic progression of lesions and viral replication in extraneural sites. Thymus contained the earliest lesions and the highest initial and subsequent viral titers. No particular cytotropism was observed as highly efficient viral replication and severe cytonecrosis proceded. Early cortical necrosis of splenic periarteriolar lymphocytic sheath was followed by lymphoblastoid repopulation of the peripheral zone. Massive bone marrow necrosis was accompained by ultrastructural evidence of VEE viral particle production in reticulum cells, rubricytes, myeloid cells, lymphoblastoid cells, and megakaryocytes. Speed, efficiency, destructiveness, and relative sensitivity of virtually all lymphoreticular and hematopoetic cells were hallmarks of virulent VEE infection in the hamster.     

Paracoccidioidomycosis: an epidemic in the Republic of Paraguay, the center of South America

The investigation done on the frequency or incidence of Paracoccidioidomycosis in the Republic of Paraguay, with the cases appeared and registered in the Institute of Pathology of Asuncion, presents an incidence rate of 0.46 per 100,000 in the total population; 0.52 per 100,000 in the population at risk. Considering the exposed masculine population the rate is 1.03 per 100,000 and for the feminine 0.02 per 100,000. The age group most affected is within the 50-54 year range with 3.54 per 100,000, the highest rate of all the groups studied. These are the incidence in a strongly exposed population which is controlled and well known. The period of 10 years (1960/69) which has been chosen for this investigation, shows a frequency of the mixed type (lymphatic-visceral or lymphoma-type) which reaches 25% of the total, and a low frequency for the pulmonary form which reaches a mere 12.5%. The mucocutaneous lesion with the involvement of the regional lymph nodes is the dominating form. Considering three consecutive 5 year periods between 1960 to 1974, no cases with proved pulmonary involvement were found until 1964; from 1965 to 1969 the percentage of pulmonary lesions in all the cases considered was 23.0% and from 1970 to 1974 reached to 38.4%. However, mucocutaneous and the lymphatic-visceral or mixed forms do not show significant variations. The rats are small and represent the incidence of this mycosis. It is suggested that a failure of the immunologic system would be found in those affected by the disease and there would be a strong resistence in the majority of the population exposed or within the endemic area of the infection.     

Humane endpoints are an objective measure of morbidity in Venezuelan encephalomyelitis virus infection of mice

The clinical signs are described of Venezuelan encephalomyelitis virus (VEEV) infection in mice after both airborne and subcutaneous (s.c.) challenge. Group clinical scores reflected the known pathogenesis of infection by both s.c. and airborne challenge, and with epizootic and enzootic strains of VEEV. This observation confirms the specific relationship of the observed clinical signs to VEEV infection. Within an experiment, those who are assessing the animals for clinical signs must have a common understanding of their appearance, including severity, and should be unaware of the allocation of treatments. If these conditions are met, the progress of clinical signs may be used to determine objectively the time of culling for humane endpoints.     

Helicobacter pylori in South America

Interviews of a representative sample of 201 physicians (general practitioners, gynecologists, pediatricians) with a mean age of 47 years show: there is a unmanageable amount of information about drugs and their risks. The physicians prefer practical experience rather than specialized literature. As a result they plead for a central authority of information with periodical reports on the current knowledge of drug-therapy and with the possibility of therapeutical consultation.     

Improved protection against Venezuelan equine encephalitis by genetic engineering of a recombinant vaccinia virus

An improved vaccine is needed against Venezuelan equine encephalitis (VEE) virus because the existing live attenuated vaccine, TC-83, causes a high incidence of adverse effects, and the Formalin-inactivated vaccine, C-84, does not protect against airborne infection. A recombinant vaccine had previously been constructed in which the VEE structural proteins were expressed by vaccinia virus. Although protection against subcutaneous challenge with VEE was achieved, the vaccine had limited efficacy against aerosolized virus. We made a similar construct (WR100) and compared its performance with that of a recombinant vaccinia virus which had been altered in two ways (WR103) in order to improve its performance as a vaccine: a synthetic promoter was inserted upstream of the VEE coding sequence to increase the amount of VEE proteins produced, and a single nucleotide in the E2 glycoprotein gene was altered to enhance immunogenicity. The WR103 virus expressed greater amounts of VEE proteins on the surface of infected cells than did WR100, and this difference was found to correspond to a 3.5-fold increase in VEE protein production. Sera from mice immunized with WR103 contained elevated levels of antibody to VEE, and enhanced protection against subcutaneous challenge with the pathogenic Trinidad donkey strain was achieved. This altered construct could form the basis for a better vaccine against VEE.     

南美的铜堆浸技术

在南美，过去的10年中铜的堆浸发展迅猛，智利是应用这一工艺最多的国家，本文主要是介绍当今智利铜堆浸设施的设计与生产实践。     

Venezuelan equine encephalitis and Oropouche virus infections among Peruvian army troops in the Amazon region of Peru

An outbreak of a febrile illness characterized by headache, ocular pain, myalgia, and arthralgia occurred during June 1994 among Peruvian army troops in Northern Peru. On June 14-16, 1994, clinical data and blood samples were obtained from eight soldiers with a febrile illness, and from 26 others who had a history of febrile illness during the past three months. A follow-up blood sample was obtained 107 days later from four of the febrile and seven of the afebrile soldiers. Serum samples were tested for dengue (DEN), Oropouche (ORO), and Venezuelan equine encephalitis (VEE) IgM and IgG antibodies by an enzyme-linked immunosorbent assay (ELISA). Virus isolation was performed by inoculation of newborn mice and Vero cell cultures. Viral isolates were identified by immunofluorescence, ELISA, and nucleotide sequencing. A VEE virus infection was confirmed in three of the eight febrile soldiers, two by virus isolation, and one by serology. Antigenic analysis indicated that one of the virus isolates was similar to VEE subtype I, variety ID, viruses previously isolated in Colombia and Venezuela. Nucleotide sequence data showed that both viral isolates were identical to one another and closely related to VEE ID viruses previously isolated in Peru, Colombia, and Venezuela. Serologic results showed that two of 26 afebrile soldiers had IgM antibody to VEE and four had IgG antibody to VEE; two febrile soldiers had IgG antibody in their first serum samples. Oropouche-specific IgM antibody was detected in one of the eight febrile and five of the afebrile soldiers, and 18 of the 34 soldiers had low titers of ORO IgG antibody titers, which did not meet the diagnostic criteria for confirmed cases. All soldiers were negative for DEN IgM antibody, and 10 had flavivirus IgG antibody that reacted with DEN antigens. These data indicated that VEE ID virus was one of the causes of illness among Peruvians soldiers and that this was the first association of this VEE subtype with human disease in Peru.     

Effect of salt concentration in larval rearing water on susceptibility of Aedes Mosquitoes (Diptera: Culicidae) to eastern equine and Venezuelan equine encephalitis viruses

The effect of salt concentration in larval rearing water on the susceptibility of adult Aedes taeniorhynchus (Wiedemann) and Aedes sollicitans (Skuse) to infection with eastern equine encephalomyelitis (EEE) virus was tested in the laboratory. Ae. sollicitans was more susceptible to infection (79%, n = 82) and viral dissemination (16%) with EEE virus than was Ae. taeniorhynchus (42%, n = 184) and (5%), respectively, when fed on a chick with a viremia of 10(7) +/- 0.1 plaque-forming units/ml; however, infection rates in adults were not affected by rearing in salt concentrations ranging from fresh water to brackish water containing 2.4% sea salts (1 part fresh water and 2 parts seawater). When fed on the same viremic 6-d-old chicken, all 48 Aedes albopictus (Skuse), reared in fresh water, became infected. Similarly, Venezuelan equine encephalitis viral infection or dissemination rates did not vary among Ae. taeniorhynchus adults that were reared in water containing 0, 1, or 2% sea salts.     

The incidence of neurological disorders in tropical South America. Experience in the Bolivian lowlands

BACKGROUND: The Chiquitano tribe lives in the southern Amazonas region in Bolivia, remote from larger towns. Data on the epidemiology of neurological disorders are completely lacking. METHODS: A combined prospective-retrospective study was designed to determine the prevalence and annual incidence of major neurological diseases. In an one-year prospective study 1514 individuals (total population 5652) who consulted the general practitioner were interviewed and examined for neurological disturbances. These histories were analysed retrospectively by a neurologist and classified according the diagnosis key of the DGN. RESULTS: During a one-year period (April 1995-March 1996), 139 patients suffering from neurological diseases were seen (one-year incidence and prevalence 2.45%). Cervical and lumbosacral pain syndromes were the most common neurological problems; these were caused by sleeping in hammocks, and by hard agricultural labour. Tropical myositis (12.9%) was very frequent and the most frequent muscle disease. Epilepsy was found in 11 patients and extrapyramidal syndromes in 2 patients. Regarding epilepsy, a high dark rate is assumed because of social and cultural traditions. Strokes are rare, since many risk factors are not present. All cases of meningitis were lethal and clearly demonstrated infrastructural problems. Patients with social diseases (AIDS, drug- and alcohol addiction, injuries caused by violence) were rarely seen. CONCLUSION: In a shrinking world, and with the development of "Tropical Neurology" as a specialised discipline neuroepidemiological data are increasingly important for two reasons. First of all, they sensitise neurologists to this topic, and secondly, they can be used to estimate the need for neurologists serving the Third World's minority populations.     

Transmission of hepatitis C in an isolated area in Japan: community-acquired infection. The South Kiso Hepatitis Study Group

BACKGROUND/AIMS: The spread of hepatitis C virus (HCV) infection not due to drug needle sharing or transfusion is largely unknown in communities. A search for risk factors for HCV infection in an endemic area might elucidate inapparent modes of transmission. METHODS: We conducted screening for hepatitis virus markers and parenteral exposures to blood among 435 inhabitants in an isolated area known for its endemicity for non-A, non-B hepatitis and in a nonendemic area with 1542 inhabitants. RESULTS: The prevalence of hepatitis B surface antigen was the same in both areas. The prevalence of antibody to HCV verified by the recombinant immunoblot assay was 32.4% in the highly endemic area and 2.3% in the nonendemic area (P < 0.001). Risk factors for HCV infection in the highly endemic area were complex but included folk remedies such as acupuncture and "vacuuming" for congested blood in muscle by the use of a warm glass bottle. CONCLUSIONS: Folk remedies such as acupuncture and cutting of the skin using nonsterilized knives should be considered as possible routes of HCV transmission not associated with blood transfusion or sharing of drug paraphernalia.     

Use of telemetry to assess vaccine-induced protection against parenteral and aerosol infections of Venezuelan equine encephalitis virus in non-human primates

Two investigational vaccines, TC-83 (live-attenuated) and C-84 (formalin-inactivated), are currently available to immunize at-risk individuals against Venezuelan equine encephalitis virus (VEE). Ideally, such vaccines should protect against both the natural mosquito-borne route of infection and from aerosol, the most common route of laboratory infection. Whereas considerable data on vaccine efficacy following parenteral challenge are available, the efficacy of these vaccines against disease caused by aerosol exposure is not well established in primates. We compared the immunogenicity and protective capacity of TC-83 and C-84 against either subcutaneous or aerosol routes of infection in cynomolgus monkeys implanted with temperature-monitoring radiotelemetry devices. A single s.c. dose of TC-83, or three s.c. doses (days 0, 7, 28) of C-84, elicited similar serum virus-neutralizing antibody responses. Animals immunized with either TC-83 or C-84 were protected against s.c. infection. In contrast, after aerosol infection, 40% of the animals vaccinated with either TC-83 or C-84 developed signs nearly as severe as those seen in unvaccinated animals. Protection was not entirely consistent with the measured preinfection immune responses: unprotected animals had serum virus-neutralizing antibody titers and lymphoproliferative responses similar to those seen in protected animals. In this study, C-84 (three doses) protected monkeys as well as TC-83 (one dose) against either a s.c. or aerosol VEE challenge.     

Group identification and intergroup attitudes: A longitudinal analysis in South Africa.

Social identity theory (SIT) and realistic conflict theory (RCT) suggest that group identification and out-group negativity will be correlated when intergroup relations involve competition and perceived threat, but the theories differ in their predictions about the direction of causality. The authors assessed Black African students' ethnic group identification and their attitudes toward English Whites, Afrikaans Whites, and Whites in general before and after South Africa's transitional election in April 1994. As predicted, Black African identification was significantly related only to attitudes toward Afrikaans Whites. Longitudinal analyses, however, suggested causal impacts from attitudes to identification and not the reverse, contradicting the SIT prediction. The authors discuss evidence for the existence of two distinct modes of group identification with different implications for intergroup behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Replicon-helper systems from attenuated Venezuelan equine encephalitis virus: expression of heterologous genes in vitro and immunization against heterologous pathogens in vivo

A replicon vaccine vector system was developed from an attenuated strain of Venezuelan equine encephalitis virus (VEE). The replicon RNA consists of the cis-acting 5' and 3' ends of the VEE genome, the complete nonstructural protein gene region, and the subgenomic 26S promoter. The genes encoding the VEE structural proteins were replaced with the influenza virus hemagglutinin (HA) or the Lassa virus nucleocapsid (N) gene, and upon transfection into eukaryotic cells by electroporation, these replicon RNAs directed the efficient, high-level synthesis of the HA or N proteins. For packaging of replicon RNAs into VEE replicon particles (VRP), the VEE capsid and glycoproteins were supplied in trans by expression from helper RNA(s) coelectroporated with the replicon. A number of different helper constructs, expressing the VEE structural proteins from a single or two separate helper RNAs, were derived from attenuated VEE strains Regeneration of infectious virus was not detected when replicons were packaged using a bipartite helper system encoding the VEE capsid protein and glycoproteins on two separate RNAs. Subcutaneous immunization of BALB/c mice with VRP expressing the influenza HA or Lassa virus N gene (HA-VRP or N-VRP, respectively) induced antibody responses to the expressed protein. After two inoculations of HA-VRP, complete protection against intranasal challenge with influenza was observed. Furthermore, sequential immunization of mice with two inoculations of N-VRP prior to two inoculations of HA-VRP induced an immune response to both HA and N equivalent to immunization with either VRP construct alone. Protection against influenza challenge was unaffected by previous N-VRP immunization. Therefore, the VEE replicon system was characterized by high-level expression of heterologous genes in cultured cells, little or no regeneration of plaque-forming virus particles, the capability for sequential immunization to multiple pathogens in the same host, and induction of protective immunity against a mucosal pathogen.